Brush holder providing resilient application of the brush against the brush holder wall



Nova 22, 1949 c. o. WEILBAECHER 2,483,783

BRUSH HOLDER PROVIDING RESILIENT APPLICATION OF THE BRUSH AGAINST THEBRUSH HOLDER WALL Filed Aug. 30, 1948 Patented Nov. 22, 1949 BRUSHHOLDER PROVIDING RESILIENT APPLICATION OF THE BRUSH AGAINST THE BRUSHHOLDER WALL Chester 0. Weilbaecher, Milwaukee, Wis., assignor toAllis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation ofDelaware Application August 30, 1948, Serial No. 46,896

9 Claims.

This invention relates to brush holders such as are used for applyingbrushes against commutators and slip rings of dynamo-electric machines.

An object of the invention is to provide an improved brush holder suchthat a given holder will accommodate a brush of any thickness within theusual range found in practice.

Another object of the invention is to provide an improved brush holdersupporting a brush for trouble-free operation for either direction ofrotation of the associated commutator.

Another object of the invention is to provide a brush holder permittingsubstantially frictionfree movement of the brush as it follows aneccentric commutator.

Another object of the invention is to provide a brush holder which willeliminate vibration or chatter resulting from friction of the brush onthe commutator.

Another object is to provide an improved brush holder in which a brushis readily inserted or removed.

Other objects and advantages will be apparent from a consideration ofthe following description taken in connection with the accompanyingdrawing, in which:

Fig. 1 is a view in side elevation of a brush holder constituting thepreferred embodiment of the present invention;

Fig. 2 is an enlarged View in side elevation of the brush holder shownin Fig. 1 having a part thereof broken away and a side plate removed;

Fig. 3 is an end view of the brush holder shown in Fig. 2;

Fig. 4 is a view in side elevation of a modification of the brush holdershown in Fig. 1;

Fig. 5 is an enlarged view in side elevation of the brush holder shownin Fig. 4 having a part thereof broken away and a side plate removed;and

Fig. 6 is an end view of the brush holder shown in Fig. 5.

Referring more particularly to the drawing by characters of reference,numeral 1 generally designates the frame of the brush holder illustratedin Figs. 1, 2 and 3, which is made of any suitable material such asbrass or steel.

The frame 7 comprises a plurality of walls 8, 9, ll]. Wall 9 has a studH extending therefrom for mounting the brush holder to a bracket l2mounted on a dynamoelectric machine. The brush holder contains a carbonbrush I4 extending radially with respect to the commutator l5 of thedynamoelectric machine as shown in Fig.

2 l. The brush it is shown as a split brush but a brush in one piece maybe used.

Resilient means are used for holding the brush l4 both against back wall9 and against the commutator 55, i. e., both peripherally and radiallywith respect to the commutator. Such means may comprise a spiral springl6 mounted in a substantially balanced cradle I! and a thrust member l3also mounted on the cradle.

The cradle l? comprises a pair of side plates l9 forming supportsmounted on a pivot 20. A pair of mass members 24, 25 are rigidly mountedon the pair of supports 19 at substantially'equal and opposite radialdistances from pivot 20. Pivot 2% extends through side walls 8 of frame1 and through the pair of supports IQ of the cradle, mass members 24, 25being remotely positioned from pivot 29 cause the cradle to have arelatively high moment of inertia. The cradle is substantially balancedin all positions by having the center of gravity thereof close to thepivot. A cotter pin 40 extending through pivot 20 between one of thecradle supports I9 and the adjoining frame side plate 8 prevents axialmovement of pivot '20.

The thrust member 18 may consist of a round rod pivotally supported fromthe lower end of the cradle by a cross pin 21 extending between cradlesupports 19. The extended portion of the thrust member It may besupported by any suitable guiding means such as a bracket 22 attached tothe frame 7. Bracket 22 has an opening '23 of larger diameter than thatof the extended portion of the thrust member to provide therein freeplay of the thrust member H3 in a radial direction. As shown, the thrustmember I8 has a rounded end which contacts the end portion of the brushadjacent commutator l5 for holding the brush against wall 9 of itschannel.

The inner end of spring I6 is inserted in a slot of a bushing it fittedover pivot 29. The outer end of the spring is free and terminates in aninversely bent portion 25 forming a thrust member applied on brush i lto force the brush radially against commutator i5.

A worm wheel 2? integral with bushing I3 is provided for winding springI6. A shaft 28 is journaled in a drilled hole 30 in upper mass member 24 and a drilled hole 3! in the lower mass member 5.75. The shaft 28 isprovided with a worm engaging the teeth of the worm wheel 21. Head 32 ofshaft 28 is slotted and has a projection 33 on its underside. Thisprojection seats in a corresponding indentation 34 in member 24 toprevent turning of the shaft 23 due to vibration and to require that theworm be lifted slightly to wind the spring I6.

Mass member 24 has an L-shaped projection 29 in which the free end ofthe spring may be inserted to free the brush when it is to be removed.

A brush guide 35 consisting of a thin metal plate is retained on the endof wall 9 adjacent commutator l by a rivet 36 extending through theguide into a drilled hole 3i of wall 9. Another drilled hole 38transversely connects with the rivet hole H. The stem of rivet 36 isflattened out where it crosses hole 38, so that the spread of the rivetlooks it in place. A pin and set screw or other known suitable meanscould also be used for supporting guide 35. Guide 35 fits loosely onrivet and extends from shoulder 39 of wall 9 into the channel containingthe brush l4. Guide 35 causes the end portion of brush [4 adjacent thecommutator to be held slightly away from wall 9, so that the brush 14contacts the surface of wall 9 only near its other end. Guide 35 fittingloosely on rivet 36 and resting on shoulder 39 is caused to pivot aboutone of its edges and is tilted slightly upward or downward about thatedge by radial movement of brush l4.

Shaft 28 is turned to wind spring [5 for adjusting the tension of thespring for obtaining desired contact pressure of brush i l on commutatorl5.

Bracket 22 and frame I define a channel for the insertion of brush M inthe brush holder. The channel may receive a crush of any thickness notexceeding the distance between guide 35 and bracket 22. The minimumbrush thickness is equal to the distance between guide 35 and thrustmember 18 in the position reached thereby when mass member 25 is appliedagainst bracket 22.

The thrust member 26 of spring i6 is applied against the end of brush i4remote from the commutator to force the brush toward the commutator. Thespring l6 reacting on brush [4 tends to rotate cradle I1counterclockwise to urge thrust member l8 against brush M to hold itagainst guide 35.

When the commutator rotates in a direction from thrust member Hi topivoted guide 35, or clockwise in Fig. l, the friction of brush M on thecommutator urges the commutator end of the brush against pivoted guideand tends to pivot the brush about guide 525. The free end of spring I 6bent to form a thrust applying member acts against the inclined outerend of brush M to hold the outer end of the brush against wall 9 as wellas to force the brush against the commutator. Thrust member l8 contactsthe brush on the opposite side and just outside the line of contact ofpivoted guide 35. In this manner, thrust members It and 26 exert onbrush M a torque about pivoted guide 35 to prevent tipping of the brushdue to the peripheral thrust exerted on the brush by rotating commutatorl5.

When the commutator rotates in a reverse direction, counterclockwise inFig. l, the force of friction urges the commutator end of the brushperipherally against thrust member it, tending to move the brush awayfrom pivoted guide 35. The tension in spring I6 is adjusted so that thecradle will hold the brush firmly against wall E! and pivoted guide 35against the force of friction acting on the brush.

In either direction of rotation the frictional forces tend to set upbrush chatter, which chatter is prevented by the damping effect ofcradle ll due to its relatively high moment of inertia.

The free end of spring iii forces the brush in its channel radiallyagainst the commutator. Due to eccentricity and other irregularities inthe commutator, the brush Hi moves radially back and forth in itschannel as it 'fOllOWs the commu tator. The brush is permitted a limitedamount of radial movement without sliding on thrust member l3 or pivotedguide 35. Thrust member l8 and pivoted guide 35 move radially with thebrush to the extent of their free play. Brush I4 is therefore providedwith substantially frictionfree movement of limited stroke to closelyfollow its associated commutator.

When the direction of rotation of the machine is reversed, brush i4remains in exactly the same position because of the absence of lostmotion in its engagement with thrust member l8 and guide 35. So-calleddouble seating of the brush is thus prevented, and the position of themagnetic axis of the armature remains undisturbed.

Another embodiment of this invention is illustrated in Figs. l, 5 and 6showing a brush holder having independent means for holding the brush inposition in its channel and of forcing it radially against a commutator.The brush holder frame comprises a pair of side walls 4| and a back wall12 defining a channel in which the brush I4 is inserted. Walls 4| arejoined at one end by wall 42 and at the other end by a rod 43.

The plates forming side walls 4! of the brush holder frame support apivot 44 extending therebetween. A spring 45 has one end anchored in abushing fitted on pivot 44. The other end 46 of the spring is free andterminates in a bent position forming a thrust member applied on the topof brush [4 to force the brush against commutator 15 of a dynamoelectricmachine.

An index wheel 47 having uniformly spaced notches 48 about the peripherythereof and integral with the bushing is provided for adjusting thetension of spring 45. A resilient latch member 4.9 has one end mountedon a plate 50 extending across the side walls 4| of the frame. The otherend of the latch member 49 is bent back to fit in a notch 48 of wheel47. The latch member is biased to bear against wheel 48 so that it looksthe Wheel to prevent unwinding of spring 45.

Another latch member 5| has one end attached to the free end 56 ofspring 45 and the other end free and bent to form a hook. Latch member5| may be used to hold the free end of spring 45 in a fixed elevatedposition by placing the hook end of the latch member'over rod 43. Thisis used when replacing a brush in the brush holder.

Another pivot 52 extends through side plates 4| and pivotally supports abalanced cradle 53 mounted thereon. The cradle is made of a solid blockof metal so that it will have a relatively high moment of inertia. Athrust member 54 is screwed through the cradle and adjustably extends tothe channel of the brush holder so that it contacts the end portion ofbrush l4 within the channel of the brush holder adjacent the commutator.

A drilled hole 56 in cradle 53 contains a spring 55 for outwardlyforcing a pin 57 inserted in drilled hole 5c over spring 55. The end ofpin 51 is rounded and contacts a flat surface of cross plate 50. Spring55 forces pin 57 against cross plate 56 of the frame, causing cradle 53to pivot to urge thrust member 5 1 laterally against brush l4 to hold itagainst wall 42 of the channel. Thrust member 54 may be made fromhexagonal bar stock and threaded lightly so as to leave flat surfaces onthe top portions of the threads. Spring 55, being applied on one of suchfiat surfaces, prevents rotation of member 54 as a result of vibrationthereof.

The brush holder may be used for either direction of rotation of thecommutator. The resilient means comprising spring 45 reacts between theframe of the holder and the end of brush I4 to force the brush radiallyin its channel against the commutator. Spring 45 also holds the end ofbrush [4 remote from the commutator against wall 42 of the brushchannel.

The cradle 53 reacts between the frame and the side of the brushadjacent the commutator to hold the brush against wall 42. Therelatively high moment of inertia of the cradle dampens any vibrationtending to rise in brush I4 due to the friction of the brush on therotating commutator.

Although but two embodiments are illustrated and described, it will beapparent to those skilled in the art that various changes andmodifications may be made therein without departing from the spirit ofthe invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. A brush holder for applying a brush in contact with a commutator,said brush holder comprising a frame including a plurality of wallsdefining a channel for said brush, a substantially balanced cradlepivotally supported in said frame, resilient means mounted in saidcradle for forcing said brush toward said commutator and for holdingsaid brush against one of the walls of said channel, and adjustabletensioning means acting between said resilient means and said cradle foradjusting the tension of said resilient means, whereby said cradle isleft free to pivot in said frame to act on said brush through saidresilient means.

2. A brush holder for applying a brush in contact with a commutator,said brush holder comprising a frame including a plurality of wallsdefining a channel for said brush, a cradle comprising a pair ofsupports mounted on a pivot in said frame at approximately the center ofgravity of said cradle, adjustable resilient means mounted in saidcradle for forcing said brush toward said commutator and for holdingsaid cradle against said brush to apply said brush against one of thewalls of said channel, and a pair of mass members mounted between saidsupports remote from said pivot on opposite sides thereof, whereby saidcradle has a high moment of inertia for damping any vibration tending tobe set up in said brush.

3. A brush holder for applying a brush in contact with a commutator,said brush holder comprising a frame including a plurality of wallsdefining a channel for said brush, a cradle comprising a pair ofsupports mounted on a pivot in said frame at approximately the center ofgravity of said cradle and a pair of mass members mounted between saidsupports remote from said pivot on opposite radii thereof for impartingto said cradle a relatively high moment of inertia, a thrust membermounted on said cradle, resilient means reacting between said frame andsaid cradle for causing said pivoted cradle to urge said thrust memberagainst said brush for holding said brush against one of the walls ofsaid channel and for damping vibrations tending to arise in such brush.

4. A brush holder for applying a brush in contact with a commutator,said brush holder comprising a frame including a plurality of wallsdefining a channel for said brush, a cradle pivotally supported in saidframe, a thrust member mounted on said cradle for contacting said brush,a spring having one end mounted in said cradle and the other end free,said free end being applied against the end of said brush for forcingsaid brush toward said commutator and for causing said pivoted cradle tourge said thrust member against said brush for holding said brushagainst one of the walls of said channel.

5. A brush holder for applying a brush in contact with a commutator,said brush holder comprising a frame including a plurality of wallsdefining a channel for said brush, a cradle supported on a pivot in saidframe at approximately the center of gravity of said cradle, said cradlecomprising a pair of supports mounted on said pivot and a pair of massmembers mounted between said supports remote from said pivot on oppositesides thereof, a thrust member mounted on said cradle for contacting theend portion of said brush adjacent said commutator, and a spring havingone end mounted in said cradle and the other end free, said free endbeing applied to the end of said brush for forcing said brush towardsaid commutator and for causing said pivoted cradle to urge said thrustmember against said brush for holding said brush against one of thewalls of said channel.

6. A brush holder for applying a brush in contact with a commutator,said brush holder comprising a frame including a plurality of wallsdefining a channel for said brush, a cradle pivotally supported in saidframe, a plurality of thrust applying members, resilient means mountedin said cradle urging one of said thrust members against the end of saidbrush for forcing said brush toward said commutator and for causing saidpivoted cradle to urge another said thrust member against said brush forholding said brush against one of the walls of said channel.

7. A brush holder for applying a brush in contact with a commutator,said brush holder comprising a frame including a plurality of wallsdefining a channel for said brush, a pivoted guide supported on saidframe for limited movement radially of said commutator, said pivotedguide extending into said channel and contacting said brush adjacentsaid commutator, a balanced cradle supported on a pivot in said frame,said cradle having a thrust member pivotally supported thereon, saidframe providing means supporting said thrust member for contacting theend of said brush adjacent said commutator, said supporting meansproviding for limited radial movement of said thrust member with saidbrush, and means comprising a spring acting between said cradle and theend of said brush remote from said commutator for forcing said brushtoward said commutator and reacting to cause said pivoted cradle to urgesaid thrust member against said brush for holding said brush againstsaid pivoted guide and one of the walls of said channel; whereby, saidthrust member and said pivoted guide provide for a substantiallyfrictionfree movement of limited radial stroke of said brush.

8. A brush holder for applying a brush in contact with a commutator,said brush holder comprising a frame including a plurality of wallsdefining a channel for said brush, a pivoted guide supported on saidframe for limited movement radially of said brush, said pivoted guideextending into said channel and contacting one side of said brush at apoint adjacent said commutator on a circle of predetermined radiusconcentric with said commutator, a balanced cradle supported on a pivotin said frame, said cradle having a thrust member pivotally supportedthereon, said frame providing means supporting said thrust member forcontacting the other side of said brush at a point outside said circle,and means comprising a spring acting between said cradle and the end ofsaid brush remote from said commutator for forcing said brush towardsaid commutator and reacting to cause said pivoted cradle to urge saidthrust member against said brush for holding said brush against saidpivoted guide and one of the walls of said channel.

9. A brush holder for applying a brush in contact with a commutator,said brush holder comprising a frame including a plurality of wallsdefining a channel for said brush, a pivoted guide supported on saidframe for limited movement radially of said commutator, said pivotedguide extending into said channel and contacting one side of said brushat a point adjacent said commutator on a circle of predetermined radiusconcentric with said commutator, a pivoted thrust member, meanssupporting said thrust member for contacting the other side of saidbrush at a point outside said circle, and resilient means for forcingsaid brush toward said commutator and for urging said thrust memberagainst said brush for holding said brush against said pivoted guide andone of the walls of said channel.

CHESTER O. WEILBAECHER.

REFERENCES CITED The following references are of record in the file ofthis patent:

